According to a first prior art, for example described in FIG. 1, it is known a classical cable comprising a cable core 11 surrounded by a cable outer sheath 12. FIG. 1 shows an example of a pulling grip fixed to a cable end according to first prior art. The cable outer sheath 12 of a cable end 10 of a cable 1 is surrounded by a pulling grip 20 of a pulling element 2. The cable end 10 has a length L10 that is below 1 m. The end 21 of pulling element 2 includes a pulling eye not shown on FIG. 1. With the help of the pulling element 2 on which a pulling effort is applied, the cable 1 can be pulled in a duct in order to be installed.
Cable 1 can be installed in a duct or in a casing by exerting a pulling force on a pulling wire that is attached to a pulling eye itself attached to the end 10 of the cable 1. When installing a cable 1 in this manner, the pulling force is exerted by the pulling grip 20 on the outer surface 12 of the cable 1, that is to say on the outer sheath 12 or on the outer jacket 12 of the cable 1.
In some cable designs, especially in optical cables without or with a limited amount of aramide underneath the outer jacket 12 and where internal elements of cable core 11 are rather loose in the design, such as for example high fiber count Flextube® cables, the pulling forces are not transferred or practically not transferred on the internal components of the cable core 11. Consequently, most of the pulling force is supported by the outer jacket 12 and the outer jacket 12 may fail, that is to say be torn, under these circumstances. The pulling grip 20, or the pulling nail which can be used instead, gets disconnected from the cable 1.
In other cable designs, especially in optical cables where internal elements of cable core 11 are rather tight in the design, the pulling forces are somewhat transferred on the internal components of the cable core 11. Consequently, only a part of the pulling force is supported by the outer jacket 12, but the outer jacket 12 may however fail, that is to say be torn, under these circumstances. The pulling grip 20, or the pulling nail which can be used instead, can get disconnected from the cable 1, even if it is for a higher pulling force than for a cable with a loose design.
In a second prior art, for example described in application WO 2000/60714 A1, it is disclosed a device for connecting the end of a wire or of a cable. This device comprises a ring provided with one or more longitudinal grooves and an end piece provided with the same number of longitudinal grooves. The grooves in the ring and the end piece form a chamber into which a wire of a cable can be inserted. When the ring is rotated over the end piece the wire(s) are grasped and locked. This device can be used for drawing wires or cables in ducts or casings. A drawback of this second prior art is a relative complexity. Indeed, it is needed to directly connect pulling element to the internal components of cable core rather than merely on the cable outer sheath.
In a third prior art, for example described in application CN101359817A, it is disclosed an integrated pulling eye with a pulling grip where slipping of the cable is prevented by using a special clamping structure in the pulling grip. A drawback of this third prior art is a relative complexity. Indeed, it is needed a specific structure of the pulling grip. Moreover, the clamping of the pulling grip on outer sheath of cable may not avoid the outer sheath to be torn if pulling force exceeds a threshold, even a relatively low one, since here again cable outer sheath is alone to bear the effect of the pulling force.